I think you are referring to phpMyAdmin. MySQL is most likely version 5.4.10. To check this click on "webstart" in the MAMP application.

To update phpMyAdmin this should work, at least this works as of version 2.1.3

1. Get the latest phpMyAdmin http://www.phpmyadmin.net/home_page/downloads.php
2. Copy the `config.inc.php` file from `/Applications/MAMP/bin/phpMyAdmin` to the desktop.
3. Delete the `phpMyAdmin` folder from `/Applications/MAMP/bin/phpMyAdmin`
4. Unzip the phpMyAdmin file you downloaded, rename the resulting folder to `phpMyAdmin` [syntax is important here] and copy it to `/Applications/MAMP/bin/`
5. Copy the `config.inc.php` file from your desktop to `/Applications/MAMP/bin/phpMyAdmin`.
6. I would suggest you make one edit to `config.inc.php`. On line 61 you will need to add a blowfish secret in between the single quotes:

Nope! That isn't the cause of the error for ME.
BUT: I use MAMP PRO in German language and so I will write my changes in GERMAN in the German bulletin...

(for me the error message was: Unknown language: de-iso-8859-1 .... so I realized, that the cause of this error is NOT a config file, but THE STRING, which is copied in the browser
if you click on the "start phpmyadmin" button.

Nope! That isn't the cause of the error for ME.
BUT: I use MAMP PRO in German language and so I will write my changes in GERMAN in the German bulletin...

(for me the error message was: Unknown language: de-iso-8859-1 .... so I realized, that the cause of this error is NOT a config file, but THE STRING, which is copied in the browser
if you click on the "start phpmyadmin" button.